1. Field of the Invention
This invention relates to the production of decamethylcyclopentasiloxane, hereinafter referred to as "the cyclic pentamer", from octamethylcyclotetrasiloxane, hereinafter referred to as "the cyclic tetramer".
2. Prior Art
Decamethylcyclopentasiloxane has been found to be increasingly useful in cosmetic formulations including anti-perspirant formulations. As a consequence, efforts in the trade are being directed towards increasing the volume of production of the cyclic pentamer.
U.S. Pat. No. 4,412,081 seeks to produce the cyclic pentamer from the cyclic tetramer by heating the cyclic tetramer in the presence of a normal C.sub.6-16 alkyl sulfonic acid and aqueous hydrogen chloride at a temperature in excess of 50.degree. C. but fails to disclose the production of the cyclic pentamer by contacting the cyclic tetramer with aqueous hydrochloric acid and a protonated amine.
U.S. Pat. No. 3,983,148 discloses a process for producing a mixture of cyclic siloxanes by hydrolyzing and condensing a hydrolyzable organo silicon compound such as dichlorodimethylsilane in the presence of aqueous hydrochloric acid and a cationic surface active agent which can be formed in situ by adding an amine, carboxylic acid, alcohol, nitrile, mercaptan, phosphine or quaternary phosphonium salt to the aqueous hydrochloric acid. There is however no disclosure or suggestion of contacting the cyclic tetramer with aqueous hydrochloric acid and a protonated amine for the purpose of converting the cyclic tetramer to the cyclic pentamer.
U.S. Pat. No. 4,447,630 discloses a method for making a mixture of cyclopolysiloxanes by hydrolyzing and condensing diorganodichlorosilanes and aqueous hydrochloric acid in the presence of a perfluorinated alkyl sulfonic acid salt but fails to disclose, teach or suggest the production of the cyclic pentamer from the cyclic tetramer by contacting the latter with aqueous hydrochloric acid and a protonated amine.
U.S. Pat. No. 4,222,952 discloses the equilibration of organosiloxanes and other rearrangements of siloxane bonds by contacting the organosiloxane with a solid perfluorinated polymer containing pendant sulfonic acid groups but fails to disclose, teach or suggest the conversion of the cyclic tetramer to the cyclic pentamer by contacting the cyclic tetramer with aqueous hydrochloric acid and a protonated amine.